Cable end construction



July 18, 1944. GQLDFIELD 2,353,719

' CABLE END CONSTRUCTION,

Filed Sept. 29, 1941 F! as 26 2:4 II

FIG"! 2a 26 ,26a e 22d '9 FIGI' 4 INVENTOR EDWIN R. GOLDFIELD ATTORN EY?Patented July 18, 1944 CABLE END CONSTRUCTION Edwin R. Goldfleld,University Heights, Ohio, as-

signor to Picker X-Ray Corporation, Waite Manufacturing Division, Inc.,Cleveland, Ohio, a corporation of Ohio 7 Application September 29, 1941,Serial No. 412,705

4 Claims.

This invention relates to improvements in the end construction of hightension cables, such as are used for instance with X-ray equipment.

An object of the present invention is to pro-' vide improved means forsecuring electrical contact members to the end of a cable with anelongated insulating sleeve adapted to coact with a complementarycontact member and all of this without disturbing the original cableconstruction and protective coatings to such an extent that the cabletends to break down under use.

The invention resides in the arrangement and manipulation of the partsas will more clearly appear from the accompanying drawing anddescription and the essential features thereof will be summarized in theclaims.

In the drawing, Fig. 1 is an elevational view of a cable end equippedwith my improved construction, a portion of a ferrule connectingassembly being broken away to more clearly show the arrangement of theparts; Fig. 2 is an enlarged central longitudinal section through theright-hand portion of the device of Fig. 1; while Figs. 3 and 4 areenlarged transverse sectional views taken along similarly numbered linesof Fig. 2.

The cable construction here shown is particularly adapted for use inconnection with the male contact member illustrated and described in myPatent No. 2,238,319, granted April 15, 1941, although it will beunderstood that the construction and principles here disclosed areapplicable for other uses.

The cable If! is of a well known type wherein a pair of electricalconductors II and I2 are covered with individual insulation and housedin an internal metallic sheath l3 which serves also as a thirdconductor. These are then covered with a very heavy layer of insulationI4 which may be of a rubber compound or the like.

Next outside of this comes a wound layer of semiconducting tape IS, anouter metallic sheath l6, and a final cover ll of cotton braid.

In the application here illustrated the conductors II, l2 and i3 are forthe filament current of the X-ray tube and the cable contacts arepreferably arranged to permit relative rotary movement between theconnected cable contacts so that the equipment may be readily handledwithout unnecessarily twisting or distorting the relatively stiffcables. To this end the three conductors are secured to contact membershaving annularly arranged concentric contact surfaces so as to permitthis relative rotation as described in my above mentioned patent. Aportion of the insulation I4 is cut away at the end of the cable so asto expose short lengths of the conductors ll, l2 and I3. A portion ofthe sheath I3 may be cut away and the rest of the sheath twisted to forma more easily connected filament. One of these conductors is soldered tothe outer contact ring it, one to the inner contact ring 20, and one tothe intermediate contact ring 19. A base 2| comprising a noncircularwafer serves as a rigid mounting for the three contact members. Thewafer here shown comprises a pair of sheets of laminated canvasimpregnated with insulating compound. A split bushing 22 surrounds thebase 2| and the extreme end Ilia of the cable I0 forming a housing forthe same. Preferably this bushing is of molded Bakelite includingshredded paper if desired, and comprises two halves 22a and 22b. Thesebushing portions may be provided with knurled spots 220 which engage theroughened surface of the cable end Illa so that in the final assemblyrelative motion between the bushing and the cable end is prevented. Anoncircular groove 22d in the bushing is complementary to the peripheraledge of the base 2| and closely surrounds and embraces the same when thebushing is in final position so as to prevent relative rotary or endwisemovement between the contact base and the bushing. An opening 22cthrough the wall of the bushing permits the pouring of a high meltingpoint insulating compound, such as rosin, into the space 23 between thecontact base and the end of the cable.

An elongated substantially rigid insulating sleeve 24 surrounds thecontact members and the split bushing and the end of the cable forseveral inches. Preferably the sleeve 24 has a length of three or fourinches or more for the purpose described in my above mentioned patent.The sleeve here shown may be of laminated paper impregnated withBakelite. On the inner end of this sleeve is threaded a plug flare 25which may be formed of molded Bakelite or other similar insulatingmaterial. A ferrule 26 of brass or the like is rigidly connected, as bysoldering, at the point 21 with the terminal end of the metallic sheathl6. This may be done by sliding the annular end of the ferrule under theend of the metallic sheath with practically no disturbance of the cablecovering at this point. It will be understood by those skilled in thisart that the formation of any slight air pockets in the cable coveringat this point eventually leads to break-down of the cable. The flaredend of the ferrule is spun over as at 26a to rigidly secure forms atight seal for a number of inches alongv the internal surface of thesleeve and provides control rings of insulating material at the points30 and 3| so as to stop the corona effect which tends to break down theinsulation during use.

In the completed device an annular groove 24a in the sleev 24 registerswith an annular groove 22 in the bushing 22. Lying partly in each ofthese grooves is a resilient corrugated split ring 32 of Vinylite,Celluloid, fiber or the like. This prevents relative longitudinalmovement between the sleeve 24 and the bushing 22.

In forming the cable end construction described above the cotton braidI! is first removed for about 6 from the end of the cable. The metalsheathing I6 is then removed to a point about 6" from the end of thecable and the tape layer I is removed for about 5 from the end of thecable. The tapered groove Inc is then ground into the rubber insulationand the extreme end of the cable is cut down to provide the shoulder lb,The heavy rubber insulation I4 is then removed for about /2" from theend of the cable to expose the conductors II, I2 and I3. The insulationis removed from these conductors and the three conductor leads aresoldered to their respective contact members. The ferrule trim cap 33and the retaining adapter ring 34 are then slipped on the end of thecable, after which the flexible conduit support assembly 35 is slid intothe proper position. It will be understood that these parts firmly holdthe cable to the housing of an X-ray tube or the like when the parts arefinally assembled for use.

The ferrul 26 with its outer flange 26a in the dot-dash condition ofFig, 2 is then slipped over the end of the cable and under the metalsheathing I6 at the point 21. The ferrule is then soldered to thesheathing. The two halves of the split bushing 22 are then placed inposition about the cable end Illa and contact base 2| and hot rosin ispoured into the space 23 and allowed to cool. The cork washer 28 is thenplaced in position and the skinned end of the cable is cleanedthoroughly with carbon tetrachloride or the like. The locking ring 32 isthen placed in the groove 22f of the bushing and the groove is coatedwith a quick drying insulating varnish having a high shearing strength,such as Glyptal. The sleeve 24 is then heated to about 200 F. and a thincoating of Glyptal is applied two inches into the inside of the sleeveat the contact end, leaving about one-half inch clean at the extremeend. The sleeve 24 is then slid over the bushing 22 until the lockingring 32 is covered. Chattertons compound is then coated over the cablefrom the ferrule 26 down to the end of the sleeve carrying the plugflare 25 which at this time is just covering the locking ring 32. Thesleeve is then moved to its final position as shown in Fig. 2, at whichtime the locking ring groove 24a will aline with the bushing groove 22fand the resilient ring will expand into both grooves. At this time theplug flare 25 will seat practically against the ferrule 26 and should beheld in this position until the Chattertons compound is cooled. Theferrule flange 25a is then spun from the dot-dash position of Fig. 2 tothe full line .position there shown and any excess sealing compound iscleaned off.

I have thus provided a cable end construction which is rather easy tomake and assemble and which firmly holds all of the parts in desiredposition when completed, while at the same time disturbing the originalcable construction by only a very small amount and that not suflicientto interfere with a long life of the cable free from break-down of theinsulation.

What I claim is:

1. A high tension cable having electrical conductors surrounded byinsulation which in turn is surrounded by a metallic sheath terminatingshort of th end of said insulation, a plurality of electrical contactmembers secured to the terminal ends of said conductors, a noncircularbase rigidly connected with said contact members, a substantially rigidinsulating sleeve open at both ends and surrounding said contact membersand said insulation from the end of said cable to a point adjacent theterminus of said sheath, said base forming the main closure means forthe terminal end of said sleeve, means sealing said sleeve to said cableinsulation, means interlocked with said noncircular base and preventingrelative movement between said contacts and said sleeve, and meansrigidly connecting said sleeve to the terminal end of said sheath.

2. A high tension cable having electrical conductors surrounded byinsulation which in turn is surrounded by a metallic sheath terminatingshort of the end of said cable, electrical contact members secured tothe terminal ends of said conductors, a substantially rigid insulatingsleeve surrounding said contact members and said insulation from the endof said cable to a point adjacent the terminus of said sheath, meanssealing said sleeve to said cable insulation, a ferrule rigidlyconnected to said sleeve and to the terminal end of said sheath, a splitbushing between the extreme end of said cable and said sleeve, meanspreventing relative endwise movement between said bushing and saidsleeve, and means preventing relative rotative movement and relativeendwise movement between said bushing and said contact members.

3. A high tension cable having electrical conductors surrounded byinsulation which in turn is surrounded by a protective sheathterminating short of the end of said cable, a plurality of annularcontact members secured respectively to the terminal ends of saidconductors, a noncircular insulating base to which said conductors arerigidly secured. substantially rigid insulating sleeve surrounding saidcontact members and said insulation from. the end of said cable to apoint adjacent the terminus of said sheath, a ferrule connecting saidsleeve and the terminal end of said sheath, high melting pointinsulating wax sealing said sleeve and said ferrule to said cableinsulation, a split bushing within said sleeve and surrounding said baseand the end of said cable, there being a groove in said bushing closelyembracing said base, said bushing having a friction contact with saidcable end preventing movement between them, high melting pointinsulating compound within sid bushing between said base and the end ofsaid cable, there being registerin annular grooves in said bushing andsaid sleeve, and a resilient corrugated ring lying in said grooves.

4. A high tension cable having a plurality of electrical conductorssurrounded by insulation common to all of them and which in turn issurrounded by a metallic sheath terminating short of the end of saidinsulation by a distance of the order of several inches, a contact base,a plurality of contact members mounted rigidly on said base, saidmembers being arcuately formed about a common center so as to berotatable relative to coacting contact members, said first named contactmembers being connected respectively to the terminal ends of saidconductors, a substantially rigid insulating sleeve open at both endsand surrounding said insulation from the end of said insulation to apoint adjacent the terminus of said sheath, means sealing said sleeve tosaid cable insulation and preventing relative rotation between them saidcontact base forming the main closure means for the terminal end of saidsleeve, means preventing relative rotation between said contact base andsaid sleeve, and means rigidly connecting said sleeve to the terminalend of said metallic sheath.

EDWIN R. GOLDF'IELD.

